Thread guides for sewing machines



Jan. 5, 1960 E. L. KOENIG 2,919,667

' THREAD GUIDES FOR SEWING MACHINES Filed April 9. 1956 Fig 6 i INVENTOR.

Edward L. Koenig WITNESS BY w w W 6% A TTORNE Y order to obtain proper positioning of the needle.

United States PatentO THREAD GUIDES FOR SEWING MACHINES 'Edward L. Koenig, Westport, Conn., assignor to The Singer Manufacturing Company, Elizabeth, N.J., a corporation of New Jersey Application April 9, 1956, Serial No. 576,926

3 Claims. (Cl. 112-218) thread in the run between the take-up and the eye of the needle, including a thread guide located at the needle clamp on the needle-bar. The thread guide on the needle clamp, in addition to serving its designed function of controlling the run of the needle thread as it maves toward the eye of the needle, also must include other characteristics such as being easy to thread and, at the same time, include means for confining the thread so that it will not escape from the guide during operation of the machine, and in addition, avoid interference With the clamping screw, the position of which is critical in Accordingly, it is. an object of this invention to provide a thread guide for the needle clamp of a sewing machine that is economical, durable, easily threaded, will adequately confine the thread to prevent escape thereof, and will efficiently perform its function of controlling the thread.

There is a problem in sewing machines in that during stitch formation, improper orientation of the needle thread relatively to the bobbin thread will result in form- 'ing so-called hitch-stitches rather than the desired perfect lock stitches, and in thread breakage. Numerous attempts have been made and are still being made to overcome this defective sewing. Of even more importance than providing an improved thread guide, having in mind the normal function of such guides, it has been found that a thread guide constructed in accordance with the present invention, eliminated thread-breakage and greatly reduced litch-stitching, as hereinafter more fully explained.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

Fig. 1 is a fragmentary elevational view of the head 'of a sewing machine having a needle clamp carrying a thread guide constructed in accordance with the present invention.

Fig. 2 is an enlarged detail view in elevation of the thread guide of Fig. 1 and illustrating fragmentary portions of the needle and needle-bar.

Fig. 3 is a sectional view taken substantially on the line 3--3 of Fig. 2.

Fig. 4 is a detail bottom plan view of the needle clamp appearing in Fig. 1.

Figs. 5 and 6 are fragmentary illustrations of work that has been sewed on the same sewing machine, with Fig.5 illustrating the stitching that is performed-when 2 v a conventional needle clamp thread guide is used and with Fig. 6 illustrating the stitching that is performed when there is used a thread guide in accordance with the present invention.

With reference to the drawings, there is illustrated in Fig. l a fragmentary portion of a sewing machine bracket arm 1 carrying a head 2. A needle-bar 3 is journaled in the head 2 in the usual manner for longitudinal reciprocation, and carries at its lower end a needle 4 secured thereto by a needle clamp 5 having mounted thereon a thread guide 6 constructed in accordance with the present invention. The head 2 also carries a tension device 7 and a take-up mechanism including a take-up lever 8. As is customary a needle thread 9 extends from the supply, through a thread guide 10, through the tension device 7 to the eye of the take-up lever 8, and finally through a pair of thread guides 11 and the needle clamp thread guide 6 to the eye of the needle 4.

The needle clamp 5 includes a body portion including a band 12 that encircles a reduced necked-down portion Fig. 4, at the lower end 13 of the needle-bar 3 and a laterally extending lug 14 having a threaded bore that receives a clamping screw 15. The shank of the needle 4 is received within a slot 16, Fig. 4, in the lower end 13 of the needle-bar 3. The end of the screw 15 bears against the periphery of the needle-bar at a point opposite the slot 16 so that upon tightening the screw 15, it will draw the opposite side of the band 12 against the shank of the needle 4 in the slot 16 and thus clamp the needle 4 to the needle-bar 3. The band 12 of the needle clamp 5 includes a flat vertically arranged front face 17 to which the thread guide 6 is secured.

The thread guide 6 consists of a sheet metal element including a planar body portion 18 that is secured to the front face 17 of the needle clamp 5 preferably by spot welding. The body portion 18 has a lower edge 21 and carries a finger 19 that includes a vertical portion 20 depending from the lower edge 21 and a horizontal portion 22 having an upper edge 23 extending laterally in spaced parallel relation to the edge 21. Since the finger 19 is an integral part of the body portion 18, the space between the lower edge 21 of the body portion and the upper edge 23 of the finger constitutes in effect a slot in the body portion through which the thread 9 is run, the depending portion 20 of the finger 19 having an inner edge 24 that comprises the closed end of the slot. As more clearly seen in Fig. 3, the finger 19 is bent at a slight angle out of the plane of the body portion 18 toward the needle to be parallel to the run of the thread 9 at that point. To reduce the width of the slot and prevent the escape of the thread therefrom during operation of the machine, there is formed a rise 25 on the edge 23 at a point spaced from the edge 24 of the depending portion 20 and extending toward the edge 21 of the body portion 18. The rise 25 could also, if desired, be formed on the edge 21.

To facilitate threading the honzontal portion 22 of the finger 19 includes a free end 26 that is bent rearwardly toward the lug 14 of the needle clamp. Extending laterally from the lower end of the body portion 18 adjacent to the open end of the slot, is a second finger 27 having a lower edge 28 that is continuous with the lower edge 21 of the body portion. The lower edge 21 of the body portion 18 is disposed vertically below the lug 14 of the needle clamp so that the finger 27 can be bent around the band 12 of the needle clamp 5 below the lug 14. As best seen in Fig. 4, the free end 26 of the finger 19 is bent rearwardly at less of an angle than is the finger 27 so that the end 26 of the finger 19 is vertically out of registry with the finger 27, or in other words, the end 26 of the finger 19 lies forwardly of the vertical projection of the finger 27. Thus in order to thread the guide 6, the thread 9 is laid against the finger 27 beyond the end 26 of the finger 19, and is drawn forwardly, which motion will cause the thread to pass behind the end 26 and into the slot between the body portion 18 and the finger 19. Extending the end of the finger 27 around the band :12 beneath the lug14 of the needle clamp, virtually precludes the possibility that the thread will pass behind the finger 26 or body portion 18 rather than into the slot.

With reference to Fig. 2, the slot is arranged wholly to one side of the needle 4 in order to secure the proper thread lead to the eye of the needle. in the particular machine illustrated, the needle is threaded from left to right, thus defining the operative threading direction whichis illustrated in the drawing by the arrow A.

From the above, it will be noted that there has been .provided by the present invention, an economical thread guide consisting only of a single sheet metal stamping which is easily accommodated on the needle clamp and is readily threaded. Of even more importance than these desired advantages, the present device also has improved 1 thread guiding characteristics that improve the stitching quality of the machine. As one example of the improved stitching, there is illustrated in Fig. 5 a sample of work sewed on a conventional oscillating shuttle family-type sewing machine with a conventional needle clamp thread guide, and in Fig. 6, there is illustrated a sample of the work sewed on the same machine but having a needle-bar thread guide in accordance with the present invention. These'samples illustrate sewing on a work piece W with silk thread at high speed and with a short stitch length. The resultant seam of stitching S in Fig. 5 includes numerous imperfect stitches H of the type commonly called hitch-stitches, and it has been found that the thread will break on many occasions. The hitch-stitches H are objectionable mainly because of resultant appearance of the seam since the hitch-st tches are staggered and the individual stitches do not define a straight line as in the case of the perfect lock stitches. When the needle clamp thread guide made in accordance with this invention is used, the resultant seam being illustrated in Fig. 6, thread breakage was minimized and hitch-stitching was virtually eliminated.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However, it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as a limitation of the invention. All such modifications which do not'depart from the spirit of the invention are intended to be included within the scope of the appended claims.

Having thus set forth the nature of the invention, what I claim herein is:

1. In a sewing machine, a vertically disposed reciprocatory needle-bar, a needle carried by said needle-bar and having a thread eye, means for securing said needle to said needle-bar comprising a needle clamp including a clamping screw extending laterally from said needle clamp, and a thread guide formed from a blank of sheet material and comprising a body portion secured to said needle clamp, said body portion presenting a substantially planar face arranged generally parallel to the axis of said needle and over which the thread runs and having a laterally extending thread slot defined by spaced parallel upper and lower edges arranged generally perpendicular to said needle and defining a tortuous path for the thread from the planar face through the thread slot to the eye of the needle, said thread slot being disposed to one side of said needle with the closed end of said slot adjacent to said needle, said slot being arranged vertically below said clamping screw, a horizontal finger extending from said body portion and having a lower edge that is continuous with the upper edge of said slot, said finger being bent around said needle clamp below said clamping screw,-the free end of the lower edge of the slot being forwardly out of vertical registry with said finger to facilitate threading of said slot.

2. In a sewing machine, a vertically disposed reciprocatory needle bar, a needle having a shank at the upper end thereof and a thread eye at the lower end thereof, said needle being arranged with saidshank overlappinglthe lower end of said needle bar, means for securing said needle to said needle bar comprising a combined needle clamp and thread guide presenting a substantially planar thread-engaging face arranged generally parallel to the axis of said needle and including a body portion encircling the lower end of said needle bar and said shank, a iug extending laterally from said body portion and receiving a needle clamping screw, and a lowerportion depending below said body portion and said lug, said lower portion having an outer face substantially in the plane of said thread-engaging face, said lower portion having an opening therethrough extending from the outer face and defined by substantially parallel upper and lower edges arranged in spaced planes normal to the axis of said needle, said opening defining a sharply tortuous thread path for the thread from the planar face, through the opening to the eye of the needle.

3. In a sewing machine in accordance with claim'Z in which the opening in said lower portion of said combined needle clamp and thread guide comprises an open-ended slot.

References Cited in the file of this .patent UNITED STATES PATENTS 423,113 Baker Mar. 11,1890 801,476 Pierce Oct. 10, 1905 1,286,410 Read Dec. 3, 1918 1,966,500 Havey July 17, 1934 2,036,959 Rubel Apr. 7, 1936 2,230,652 Nelson 'Feb. 4,1941 

